Re: [PATCH] omap_vout: find_vma() needs ->mmap_sem held

[Al Viro]

On Sun, Dec 16, 2012 at 09:01:10PM +0100, Paul Bolle wrote:
> > +   vma = find_vma(mm, virtp);
> >     } else if (vma && (vma->vm_flags & VM_IO) && vma->vm_pgoff) {
> 
> Shouldn't that line become 
>     if (vma && (vma->vm_flags & VM_IO) && vma->vm_pgoff) {
> 
> so that this actually compiles?

*Do'h*

Yes, it should.  Mea culpa...

Signed-off-by: Al Viro <v...@zeniv.linux.org.uk>
---
diff --git a/drivers/media/platform/omap/omap_vout.c 
b/drivers/media/platform/omap/omap_vout.c
index 9935040..cb564d0 100644
--- a/drivers/media/platform/omap/omap_vout.c
+++ b/drivers/media/platform/omap/omap_vout.c
@@ -207,19 +207,21 @@ static u32 omap_vout_uservirt_to_phys(u32 virtp)
        struct vm_area_struct *vma;
        struct mm_struct *mm = current->mm;
 
-       vma = find_vma(mm, virtp);
        /* For kernel direct-mapped memory, take the easy way */
-       if (virtp >= PAGE_OFFSET) {
-               physp = virt_to_phys((void *) virtp);
-       } else if (vma && (vma->vm_flags & VM_IO) && vma->vm_pgoff) {
+       if (virtp >= PAGE_OFFSET)
+               return virt_to_phys((void *) virtp);
+
+       down_read(&current->mm->mmap_sem);
+       vma = find_vma(mm, virtp);
+       if (vma && (vma->vm_flags & VM_IO) && vma->vm_pgoff) {
                /* this will catch, kernel-allocated, mmaped-to-usermode
                   addresses */
                physp = (vma->vm_pgoff << PAGE_SHIFT) + (virtp - vma->vm_start);
+               up_read(&current->mm->mmap_sem);
        } else {
                /* otherwise, use get_user_pages() for general userland pages */
                int res, nr_pages = 1;
                struct page *pages;
-               down_read(&current->mm->mmap_sem);
 
                res = get_user_pages(current, current->mm, virtp, nr_pages, 1,
                                0, &pages, NULL);
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